Color-television signal-translating stage



FFFfFF'I-f March 7, 1944. J. c. wlLsoN COLOR-TELEVISIONSIGNAL-TRANSLATING STAGE Filed Sept. 6. 1941 INVENTOR OHN C. WILSON.

ATTORNEY aS-'I Patented Mar. v'1, 1944 COLOR-TELEVISIONSIGNAL-TRANSLATING STAGE John C. Wilson, Bayside, N. Y., assignor toHazeltine Corporation, a corporation ot Dela- Ware Application September6, 1941, Serial No. 409,847

(Cl. P18-5.4)

9 Claims.

This invention relates to color-television signal-translating stagesand, particularly, to such stages of the type including a cathode-raytube having an electrode adapted to be scanned by electrons of variablevelocity.

In some television signal-translating systems it is desirable to scan anelectrode of a cathode-ray tube with a beam of electrons of controllablevelocity. Hitherto, it has not been possible to secure a satisfactoryscansion under such conditions for the reason that the deflection of thecathode-ray beam of such tube by the scanning eld is dependent upon thevelocity of the electrons in the beam. Thus, in general, if an electrodein a cathode-ray tube is being scanned and the voltage of anaccelerating electrode is changed to vary the velocity of the electronbeam, the area of the electrode which is scanned simultaneously changesdue to the different effect of the scanning field on the electron beamof different velocity. Specifically, if the voltage of theelectron-scanning beam is raised and the beam velocity is therebyincreased, the deection caused by a given scanning iield is decreased,resulting in a scanned raster of decreased size on the scannedelectrode, and vice versa.

It is an object of the present invention, therefore, to provide animproved color-television signal-translating stage of the general typeunder consideration which is not subject to one or more of theabove-mentioned disadvantages of arrangements of the prior art.

It is another object of the invention to provide an arrangement for useas a color-television signal-translating stage which is effective toscan an electrode in a cathode-ray tube with an electron beam ofvariable velocity and in such manner that the scanning deflection of theelectron beam is independent of the velocity of the electrons incidenton the electrode scanned.

It is still another object of the invention to provide an improved colortelevision signalreproducing system.

In accordance with the invention, a colortelevision signal-translatingstage comprises a cathode-ray tube, an electron gun structure in thetube for forming and accelerating an electron beam, a rst scannedelectrode, and means for applying a substantially constant voltage tothe rst electrode and for producing low-velocity electrons in thevicinity of the flrst electrode. The stage also comprises means fordeveloping a deflecting field for the beam between the electron gunstructure and the first electrode to scan the electrode adapted tofluoresce with a color dependent upon the velocity of the electronsincident thereon and effectively screened from the electron gunstructure by the rst electrode, and means for applying a variablevoltage to the second electrode to accelerate the low-velocity electronsto the second electrode and control their velocity at the secondelectrode. By this arrangement, the second electrode is scanned byelectrons of variable velocity to produce a color image of thetranslated signal and the scanning vision signal receiver of thesuperheterodyne type embodying a television signal-translating stage inaccordance with the present invention.

Referring now more particularly to the drawing, the system illustratedcomprises a color telefirst electrode with the beam, a second scannedvision signal receiver of the superheterodyne type including an antennasystem I0, II connected to a radio-frequency amplifier I2 of one or morestages, to which is connected in cascade, in the order named, anoscillator-modulator I3, an inintermediate-frequency amplifier I4 of oneor more stages, a detector and A. V. C. supply l5, a videofrequencyamplifier i6 of one or more stages, and an image-reproducing device I'I.A line-scanning generator I8 and a eld-scanning generator I 9 arecoupled to an output circuit of detector I5 through asynchronizing-signal separator 2D and have output circuits coupled,respectively, to linescanning plates Z2, 23 and field-scanning plates2li, 25 of cathode-ray signal-reproducing device I7. A unidirectionalvoltage is derived from detector and A. V. C. supply I5 and applied toone or more of the tubes of radio-frequency amplifier I2,oscillator-modulator I3, and intermediatefrequency amplifier IB tocontrol the amplification of the signal-translating channel of thereceiver and thereby maintain the signal input to detector I5 within arelatively narrow amplitude range for a Wide range of received signalintensities. A sound-signal reproducer 26 is coupled to an outputcircuit of intermediate-frequency amplier I for translating andreproducing sound signals accompanying the received television program.The stages or units I0I6, inclusive, l8-2, inclusive, and 25 may all beof conventional wellknown construction so that detailed illustration anddescription thereof are unnecessary herein.

Referring briefly, however, to the operation of the system describedabove, television signals intercepted by antenna circuit I0, II areselected and amplified in radio-frequency amplier I2 and applied t theoscillator-modulator I3 wherein they are converted intointermediatefrequency signals which,vin turn, are selectively amplied inintermediate-frequency amplifier I4 and delivered to detector I5. Themodulation components of the signal are derived by detector I5 and aresupplied to video-frequency amplifier I5 wherein they are amplied andfrom which they are supplied in the usual manner to a brilliancy-controlelectrode of image-reproducing device I1. synchronizing componentsderived in detector I5 are separated from the video-frequency componentof the signal in synchronizing-signal separator 20 and applied tosynchronizing control elements of generators I8 and I9. The intensity ofthe scanning ray of device I1 is thus modulated or controlled inaccordance with the video-frequency voltages impressed on the controlelectrode in the usual manner. Scanning potentials are generated inline-scanning and held-scanning generators I8 and I9, which arecontrolled by synchronizingvoltage pulses derived from separator 20, andapplied to the scanning plates of image-reproducing device I1 to produceelectric scanning elds, thereby to deflect the scanning ray in twodirections normal to each other so as to trace a rectilinear scanningpattern and thereby reconstruct the reproduced image. tional controlpotential, derived from unit l5 and applied to one or more tubes of thepreceding stages, serves to maintain the amplitude of the signal inputto detector I5 within a relatively narrow range for a wide range ofreceived signal amplitudes. Sound signals accompanying the receivedtelevision program are reproduced in sound-signal reproducer 26 in aconventional manner.

Referring now more particularly to the portion of4 the system embodyingthe invention, the color signal-translating stage comprising cathode-raytube I1 includes an electron gun structure for forming an electron beam.This electron gun structure includes cathode 30 and rst and secondaccelerating anodes 3l and 32. The cathode-ray tube I1 also comprises arst scanned electrode 33 and means for applying a substantially constantvoltage thereto further to accelerate the electrons of the beam. Theterm constant voltage isintended to refer to a voltage which is constantwith reference to cathode 30. First electrode 33 is constructed ofsecondary-emissive material and the low-velocity electrons are producedin the vicinity thereof when the high-voltage scanning beam ofcathode-ray tube I1 becomes incident thereon. First scanned electrode 33comprises a plurality of elementary upset tabs or projections thereonwhich are effective to block the direct path of electrons from cathode30 through elementary apertures thereof. lAn electrode of this generaldescription is described in United States Patent No. 2,280,191, grantedon April 21, 1942, to Rudolf C. Hergenrother, led September 30, 1939.Denecting plates 22, 23 and 24, 25 provide means for developing adeflecting eld for the beam between the electron gun structure 30, 3|,32 and the rst scanned electrode 33 to The unidirecscan the beam overthe nrst scanned electrode 33. A second scanned electrode 34, which iseffectively screened from the electron gun structure by the firstscanned electrode 33, is disposed adjacent thereto. The second scannedelectrode 34 comprises a backing plate of semitransparent conductivematerial having on one surface thereof a coating of uorescent material35 adapted to iluoresce at a color dependent upon the velocity of theelectrons incident thereon.

In order to vary the voltage of the second scanned electrode 34 andthereby to accelerate the low-velocity secondary electrons generated atelectrode 35 to, and control their velocity at, the second scannedelectrode 34, there is provided a color signal amplifier and detector 3Ghaving an input circuit connected to intermediate-frequency amplier I4and an output circuit connected to second scanned electrode 34.

In considering the operation of the portion of the system constitutingthe present invention, it will be assumed that the received colortelevision signal is accompaniedby a color-indicating television controlsignal. This color-indicating signal may be a signal the amplitude ofwhich varies in accordance with the color being transmitted through thetelevision system at any particular instant. This variable controlsignal may be transmitted with the received video-frequency componentsof the color television signal as amplitude modulation on a suitablecarrier wave in the same way that the sound signals accompanying thereceived television program are transmitted. The color signal detectorand amplifier 36 is leffective to detect these color-indicatingmodulation components and amplify them to provide a undirectionaloperating voltage for second scanned electrode 34. By this arrangementthe operating voltage of anode 34 is dependent upon the color beingtransmitted by the system at a lparticular instant and the fluorescentcoating 35 is effective to fluoresce with a color dependent upon thevelocity of electrons incident thereon. The voltage of second scannedelectrode 34, therefore, determines the velocity of the electrons whichare incident on the uorescent material 35 and thereby determines thecolor of the image element reproduced.

In summary, therefore, it is seen that the arrangement of the inventioncomprises a color television signal-translating stage includingcathode-ray tube I1 which has an electron gun I structure for formingand accelerating an electron beam, this electron gun structurecomprising cathode 30 and accelerating first and second anodes 3| and32. The cathode-ray tube l1 also includes a rst scanned electrode 33,means for applying a substantially constant voltage to the rst electrode33 and for producing low-velocity secondary electrons in the Avicinityof the first electrode 33 or, specifically, at a point near the firstelectrode at which the cathode-ray beam is incident, and means includingdeflecting plates 22, 23 and 24, 25 for developing a deflecting iieldfor the beam of tube I1 between the electron gun structure comprisingcathode 3D and the first electrode 33 to scan the nrst electrode 33 withthe electron beam. The stage further comprises a second scannedelectrode 34, adapted to fluoresce with a color dependent upon thevelocity of the electrons incident thereon and effectively screened fromthe electron gun structure including cathode 3|! by the first electrode33, and means, including unit 36, for applying a variable voltage to thesecond electrode 34 to accelerate the low-velocity secondary electronsdeveloped at first electrode 33 to the second electrode 36 and contolthe velocity of these electrons at the second electrode 34. By thisarrangement, the second electrode 34 is scanned by electrons of variablevelocity to produce a color image of the translated signal while thescanning denection at the second electrode is independent of thevelocity of the electrons incident thereon. The projections on iirstelectrode d comprise means for preventing the direct passage ofelectrons of the beam from cathode 3D through the first electrode 33 tothe second electrode Sil.

While the invention has been illustrated as used in a color televisionsystem, it will be understood that it is not limited to use in such asystem but may be used in any television signal-translating stage toscan an electrode in a cathode-ray tube with an electron beam ofvariable velocity in such manner that the scanning deflection of theelectron beam is independent of the velocity of the electrons incidenton the electrode scanned.

A fluorescent material which exhibits a change of color dependent uponthe velocity of electrons incident thereon, as described above, iscadmium sulphide which has a yellowish cast when lowvelocity' electronsare .incident thereon and a bluish cast when high-velocity electrons areincident thereon.

While there has been described what is at present considered to be thepreferred embodiment of the invention, it will be understood by thoseskilled in the yart that various changes and modications may be madetherein Without departing from the invention, and it is, therefore,aimed in the appended claims to cover all such modifications and changesas fall within the spirit and scope of the invention.

What is claimed is:

l. A color television signal-translating stag; comprising, a cathode-raytube, an electron gun structure in said tube for forming andaccelerating an electron beam, a first scanned elec* trode, means forapplyingA a substantially con stent voltage to said first electrode andfor producing low-velocity electrons in the vicinity of said firstelectrode, means for developing a deecting field for said beam betweensaid electron gun structure and said first electrode to scan said firstelectrode with said beam, a second scanned electrode adapted toiiuoresce with a color dependent upon the velocity of electrons incidentthereon and eifectively screened from said electron gun structure bysaid first electrode, and means for applying a variable voltage to saidsecond electrode to accelerate said low-velocity electrons to saidsecond electrode and control their velocity at said second electrode,whereby said second electrode is scanned by electrons of variablevelocity to produce a color image of the translated signal and thescanning deflection at said second electrode is independent of thevelocity of the electrons incident thereon.

2. A color television signal-translating stage comprising, a cathode-raytube, an electron gun structure for said tube for forming andaccelerating an electron beam, a first scanned electrode, means forapplying a substantially constant voltage to said rst electrode and forproducing lowvelocity electrons in the vicinity of said rst electrode,means for developing a deflecting field vfor said beam between' saidelectron gun structure and said first electrode to scan said rstelectrode with said beam, a second scanned electrode adapted toiiuoresce with a color dependent upon the velocity of electrons incidentthereon and eifectively screened from said electron gun structure bysaid first electrode, means responsive to a television signal forapplying a variable voltage'to said second electrode to accelerate saidlow-velocity electrons to said second yelectrode and control theirvelocity at said sccond electrode, whereby said second electrode lsscanned by electrons of variable velocity to produce a color image ofthetranslated signal and the scanning deflection at said second electrodeis independent of the velocity of the electrons incident thereon.

3. A color television signal-translating stage for a television receivercomprising, a cathode-ray tube, an electron gun structure for said tubefor forming and accelerating an electron beam, a first scannedelectrode, means for applying a substantially constant voltage to saidfirst electrode and for producing low-velocity electrons in the vicinityof said rst electrode, means for developing a deiiecting iield for saidbeam between said electron gun structure and said rst electrode to scansaid first electrode with said beam, a second scanned electrode adaptedto fluoresc with a color dependent upon the velocity of electronsincident thereon and effectively screened from said electron gunstructure by said first electrode, means responsive to a receivedcontrol signal for applying a variable voltage to said second electrodeto accelerate said low-velocity electrons to said second electrode andcontrol their velocity at said second electrode, whereby said secondelectrode is scanned by electrons of variable velocity to produce acolor image of the translated signal and the scanning deflection at saidsecond electrode is independent of the Velocity of the electronsincident thereon. I

4. A color television signal-translating stage comprising, a cathode-raytube, an electron gun structure in said tube for forming andaccelerating an electron beam, a rst scanned electrode, means forapplying a substantially constant voltage to said iirst electrode andfor producing lowvelocity electrons in the vicinity of said firstelectrode, means for modulating said beam in accordance with thetranslated television signal, means for developing a deiiecting eld forsaid beam between said electron gun structure and said first electrodeto scan said first electrode with said beam, a second electrode adaptedto iiuoresce with a color dependent upon the velocity of electronsincident thereon and eifectively screened from said electron gunstructure by said first electrode, and means for applying a variablevoltage to said second electrode to accelerate said low-velocityelectrons to said second electrode and control their velocity at saidsecond electrode, whereby said second electrode is scanned by electronsof variable velocity modulated in accordance with said television signalto produce a color image of the translated signal and the scanningdeflection at said second electrode is independent of the velocity ofthe electrons incident thereon.

5. A color television signal-translating stage comprising, a cathode-raytube, an electron gun structure in said tube for forming andaccelerating an electron beam, a first scanned electrode including asurface of secondary-emissive material, means for applying asubstantially constant voltage to said rst electrode and for producinglow-velocity secondary electrons at the point at which said beam isincident on said rst electrode, means for developing a deiiecting eldfor said beam between said electron gun structure and said rst electrodeto scan said first electrode with said beam, a second scanned electrodeadapted to fluoresce with a color dependent upon the velocity ofelectrons incident thereon and effectively screened from said electrongun structure by said iirst electrode, means forapplying a variablevoltage to said second electrode to accelerate said low-velocityelectrons to said second electrode and control their velocity at saidsecond electrode, whereby said second electrode is scanned by electronsof variable velocity to produce a color image of the translated signaland the scanning deiiection at said second electrode is independent ofthe velocity of the electrons incident thereon. l

6. A color` teleii'sion signal-translating stage comprising,acathodeiray tube, an electron gun structure in said tube for formingand accelerating an electron beam, -a first scanned electrode, means forapplying a substantially constant voltage to said rst electrode and forproducing lowvelocity electrons in the vicinity of said first electrode,means for preventing the direct passage of high-velocity electrons ofsaid beam through said first electrode,-m eans for developing adeiiecting iield for said beam between said electron gun structure andsaid iirst electrode to scan said iirst electrode with said beam, asecond scanned electrode adapted to iiuoresce with a color dependentupon the velocity of electrons incident thereon and effectively screenedfrom said electron gunstructure by said rst electrode, and means forapplying a variable voltage to said second electrode to accelerate saidlow-velocity electrons to said second electrode and control theirvelocity at said second electrode, whereby said second electrode isscanned by electrons of variable Velocity to produce a color image ofthe translated signal and the scanning deflection at said secondelectrode is independent of the velocity of the electrons incidentthereon.

'1. A color television signal-translating stage comprising, acathode-ray tube, an electron gun structure in said tube for forming andaccelerating an electron beam, a first scanned electrode, means forapplying a substantially constant voltage to said first electrode andfor producing lowvelocity electrons in the vicinity of said firstelectrode, means for developing a deecting eld for said beam betweensaid electron gun structure and said rst electrode to scan said firstelectrode with said beam, a second scanned electrode having a surface offluorescent material adapted to uoresce with a color dependent upon thevelocity of electrons incident thereon and eiectively screened from saidelectron gun structure by said rst electrode, and means responsive to acolorcontrol signal for applying a predetermined voltage to said secondelectrode to accelerate said low-velocity electrons to said surface ofiiuorescent material and control their velocity at said uorescentmaterial, whereby said fluorescent material is scanned by electrons ofvariable velocity to produce a color image of the translated signal andthe scanning deflection at said fluorescent material is independent ofthe velocity of the electrons incident thereon.

8. A color television signal-translating stage comprising, a cathode-raytube, an electron gun structure in said tube for forming andaccelerating an electron beam, a first scanned electrode, means forapplying a substantially constant voltage to said iirst electrode forproducing low-velocity electrons in the vicinity of said irst electrode,means for developing a defiecting eld for said beam between saidelectron gun structure and said first electrode to scan said firstelectrode with' said beam, a second scanned electrode comprising asurface of fluorescent material the color of which changes with thevelocity of electrons incident thereon and eiectively screened from saidelectron gun structure by said iirst electrode, and means for applying avariable voltage to said secondrelectrode to accelerate said lowvelocityelectrons to said second electrode and control their velocity at saidsecond electrode, whereby said second electrode is scanned by electronsof variable velocity to produce a color image of the translated signaland the scanning deflection at said second electrode is independent ofthe velocity of the electrons incident thereon.

9. A color television signal-translating stage comprising a cathode-raytube, an electron gun structure in said tube for forming andaccelerating an electron beam, a rst scanned electrode, means forapplying a substantially constant voltage to said first electrode andfor producing lowvelocity electrons in the vicinity of said iirstelectrode, means for developing a deiiecting field for lsaid beambetween said electron gun structure and said iirst electrode to scansaid rst electrode with said beam, a second scanned electrode comprisinga surface of fluorescent material adapted to iiuoresce with a colordependent upon the velocity of electrons incident thereon and asemitransparent conductive backing plate eiec'tively screened from saidelectron gun structure by said iirst electrode, and means for applying avariable voltage to said backing plate to accelerate said low-velocityelectrons to said fluorescent material and control their velocity atsaid iiuorescent material, whereby said second electrode is scanned byelectrons of variable velocity to produce a color image of thetranslated signal and the scanning deflection at said second electrodeis independent of the velocity of electrons incident thereon.

JOHN C. W'ILSON.

